Histology of GIT
Liver
Dr Nusrat Zareen
Assistant Professor Anatomy
Feb 15, 2011.
Learning objectives of liver histology
At the end of the session , you should be able to:
1. Recall the ULTRASTRUCTURE of hepatocytes.
2. Narrate the structural architecture of liver. (hepatic cords, sinusoids,
space of Disse,)
3. Draw and identify the hepatic lobule.
4. Name the structures present in the portal triad.
5. Describe the 3 interpretations of the liver structure. (classic lobule, portal
lobule, liver acinus).
6. Describe the histological features of intra hepatic duct system.
7. Describe the dual blood supply of liver.
8. Relate the liver zones with the functional heterogenicity of the
hepatocytes.
Functions of liver
• Metabolic achievements in control of
synthesis and utilization of carbohydrates,
lipids and proteins.
• Secretory and excretory functions,
particularly with respect to the synthesis of
secretion of bile.
• Vascular functions, including formation of
lymph and the hepatic phagocytic system.
Main Functions of hepatocytes
• form and secrete bile
• store glycogen
• metabolize cholesterol and fat
• synthesize plasma proteins
• detoxify many drugs and other poisons
• process several steroid hormones and vitamin D
Hepatocytes have lots of
everything. . . . !
• lots of mitochondria,
• lots of ribosomes,
• lots of Golgi bodies,
• lots of endoplasmic reticulum (both rough and
smooth),
• lots of stored glycogen,
• lots of lysosomes,
• lots of plasma membrane (with microvilli on the free
surface).
• They even have lots of nucleus (yes, hepatocytes may
be polyploid and commonly have two full-size nuclei).
Ultrastructure of a hepatocyte. RER, rough endoplasmic
reticulum; SER, smooth endoplasmic reticulum.
THE STROMA- Connective tissue
capsule, and delicate fibrous network
Liver cells are arranged into thousands
polygonal lobules.
The liver is organized into lobules
Unique configuration of hepatocytes-
inter connected plates - CORDS
Hepatic lobules
The portal triad/canal/area
At portal triad; see portal vein,
hepatic artery and bile duct
The hepatic sinusoids
The hepatic cords/plates- HIGHER
MAGNIFICATION !!
Sinusoids drain into the central vein
Cord like arrangement of hepatocytes, with
sinusoids HIGHER MAGNIFICATION !!
Portal & hepatic blood mixes in the sinusoids
2 noteworthy ells associated with
sinusoids :
• Stellate macrophages (KUPFFAR CELLS).
• Fat storing cells (ITO CELLS)
The space of Disse
Dual blood supply liver
1. The hepatic portal vein brings to the liver all of the
blood which has previously passed through the
intestine and spleen.
2. The hepatic artery brings fresh, oxygenated blood
from the aorta.
Portal venous blood from the intestine and spleen and
arterial blood from the aorta mix together in hepatic
sinusoids before leaving the liver in the hepatic vein.
The liver receives over 25% of the total resting cardiac
output and is responsible for over 20% of the body's
resting oxygen consumption.
Dual blood supply
The duct system of liver
Bile canaculi and ductules
Mixing of hepatic arterial and portal
venous blood in the sinusoids
3 interpretations of liver
structure
1. Classic hepatic
lobule.
2. Portal lobule.
3. Hepatic acinus
Three unit lobules of the liver
CLASSIC LOBULE- hexagonal
• Classic liver lobule,
Hexagonalin shape
• Obvious in pig, lobules are
separated by thin CT
• Central vein in the center
• Portal triads at the
periphery
• Based on the blood flow in
the sinusoids toward the
central vein
• EMPHASIZES ON THE
ENDOCRINE FUNCTION OF
LIVER.
PORTAL LOBULE- Triangular in shape
• Portal lobule, -Triangular in
shape
• –Connecting 3 central veins
at the apex
• –Portal triads are at the
center of the lobule
• –Based on the bile flow,
which is opposite of the
blood, from center to
periphery
• –Emphasizes the exocrine
functions of liver
Liver acinus(of Rappaport) -
Diamond shaped area
• between 2 neighboring
central vv & 2 triads
• Based on the blood flow
in the branches of portal
vein
• Provides best correlation
b/w blood perfusion,
metabolic activity and
liver pathology
• BASED ON THE BLOOD
AND NUTRIENT SUPPLY
OF LIVER
Structural units - liver
Liver lobule and Liver acinus with 3
zones
Liver acinus is a functional interpretation of
liver organization
Different behavior of
hepatocytes in different zones
• Zone 1 will be the first to alter incoming
blood or to be affected by it (sugar,
alcohol,….. any toxic)
• First zone to receive glucose and store as
glycogen after feeding
• First zone to breakdown glycogen and release
as glucose after fasting
Ischemic necrosis is
most severe in zone 3 in
patient with congestive
heart failure
Fatty liver
Cirrhotic liver
Thank you !
